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-   -   Wiring SPA/Hot tub (https://www.askmehelpdesk.com/showthread.php?t=366735)

  • Jun 19, 2009, 08:29 AM
    brian421
    Wiring SPA/Hot tub
    I am contemplating installing a SPA on my back patio slab. My 150 ampere panel is about 100 ft away. My plan is to run 6/3 along my outside eave (does this need to be in conduit?) and down an outside wall to the sub panel, because I live on a slab and do not have any other choice. My dilemma is once I get the feed to the sub panel (with 50 amp GFCI) I have to get it across 12' of concrete slab to the tub location. What are my choices with this? Can I run conduit across the slab? Ugly but I am not sure what other solutions there are.

    Thanks

    Brian
  • Jun 19, 2009, 10:51 AM
    tkrussell
    Quote:
    My plan is to run 6/3 along my outside eave (does this need to be in conduit?)
    Whatever you use must be rated for wet location. NM-B Romex cable is not allowed in this location. Either UF cable, MC cable, or conduit with pulled THHN/THWN conductors will be allowed.

    Conduit would look the best, I think.


    Quote:
    , because I live on a slab and do not have any other choice. My dilemma is once I get the feed to the sub panel (with 50 amp GFCI) I have to get it across 12' of concrete slab to the tub location. What are my choices with this? Can I run conduit across the slab? Ugly but I am not sure what other solutions there are.
    In this case where conduit must lay exposed on a slab, it will be subject to physical damage. Either steel rigid conduit or PVC Schedule 80 will be allowed.
  • Jun 19, 2009, 10:56 AM
    brian421
    Quote:
    Originally Posted by tkrussell View Post
    Whatever you use must be rated for wet location. NM-B Romex cable is not allowed in this location. Either UF cable, MC cable, or conduit with pulled THHN/THWN conductors will be allowed.

    Conduit would look the best, I think.




    In this case where conduit must lay exposed on a slab, it will be subject to physical damage. Either steel rigid conduit or PVC Schedule 80 will be allowed.
    What is MC cable?
  • Jun 19, 2009, 11:00 AM
    tkrussell

    See:

    http://www.alliedeg.com/pdf/afc_mcsteel.pdf
  • Jun 19, 2009, 11:13 AM
    brian421

    Thanks, you have been a tremendous help. If my hot tub is rated at 50 amps what is the minimum wiring I can use? 6/3?
  • Jun 19, 2009, 11:21 AM
    tkrussell

    Yep.
  • Jun 19, 2009, 01:33 PM
    tkrussell
    I meant to mention this before, what is the chance of saw cutting the slab and chipping out a trench to lay conduit into, and avoid the physical damage issue, and a serious tripping hazard?
  • Jun 20, 2009, 06:11 AM
    brian421
    Quote:
    Originally Posted by tkrussell View Post
    I meant to mention this before, what is the chance of saw cutting the slab and chipping out a trench to lay conduit into, and avoid the physical damage issue, and a serious tripping hazard?
    If I do cut the slab am I still required to go 18" deep (I am in South Jersey).
  • Jun 20, 2009, 08:10 AM
    stanfortyman
    No, only 4" of concrete is required above PVC outside.

    Also, you cannot use UF cable for any of the outside portion of this wiring, and any MC cable you use must be "listed for the location". They do sell underground MC cable but it is near impossible to fine, at least in most parts of the US.
  • Jun 21, 2009, 06:48 AM
    brian421
    Quote:
    Originally Posted by stanfortyman View Post
    No, only 4" of concrete is required above PVC outside.

    Also, you cannot use UF cable for any of the outside portion of this wiring, and any MC cable you use must be "listed for the location". They do sell underground MC cable but it is near impossible to fine, at least in most parts of the US.
    So if I use conduit what can I run? Can I run 6/3 NM inside and through conduit (shed 40 or 80) outside?
  • Jun 21, 2009, 07:05 AM
    tkrussell
    Do not pull NM through exterior conduit, not allowed as NM is rated for dry locations only.

    Pulling NM, esp #6-3, is not done other than a short sleeve through walls or for protection. Conduit needs to be grossly oversized to handle NM cable.

    PVC Sch 40 is fine. Need to check local codes as many require steel as PVC rises out of concrete.

    Not sure where Stan came up with 4 inch covering over conduit. Table 300.5 of the NEC allows a min of 2 inch,althou deeper is better.

    You could do this run entirely in PVC Sch 40, even where exposed under th eave.

    Horizontal runs of PVC need added straps, as PVC sags. Long runs, esp when exposed to sunlight, need expansion couplings, as PVC expands and contracts greatly.
  • Jun 21, 2009, 07:09 AM
    brian421
    Quote:
    Originally Posted by tkrussell View Post
    Do not pull NM thru exterior conduit, not allowed as NM is rated for dry locations only.

    Pulling NM, esp #6-3, is not done other than a short sleeve thru walls or for protection. Conduit needs to be grossly oversized to handle NM cable.

    PVC Sch 40 is fine. Need to check local codes as many require steel as PVC rises out of concrete.

    Not sure where Stan came up with 4 inch covering over conduit. Table 300.5 of the NEC allows a min of 2 inch,althou deeper is better.

    You could do this run entirely in PVC Sch 40, even where exposed under th eave.

    Horizontal runs of PVC need added straps, as PVC sags. Long runs, esp when exposed to sunlight, need expansion couplings, as PVC expands and contracts greatly.


    So for conduit my only option is THNN? Can't I use 1" conduit for 6/3 NM or UF?
  • Jun 21, 2009, 07:15 AM
    tkrussell
    NM is not allowed in exterior conduit. Exterior conduit is a wet location.

    UF cable is rated for wet location.

    If you insist to pull cable through conduit, do it at your own risk.

    You will be sorry for trying, unless the conduit is oversized, even then there will be problems.

    Wire pulled through conduit can be individual conductors with THHN/THWN, be sure it is rated THWN, or XHHW.
  • Jun 21, 2009, 09:13 AM
    stanfortyman
    Quote:
    Originally Posted by tkrussell View Post
    Not sure where Stan came up with 4 inch covering over conduit. Table 300.5 of the NEC allows a min of 2 inch,althou deeper is better.
    NEC T300.5, Column 3, fourth row down.

    The 2" number is in row 2 and let's you go to 12" instead of 18" if there is 2" of concrete above it.
  • Jun 21, 2009, 09:28 AM
    tkrussell
    I am using Note #2 at the bottom. If saw cutting into concrete slab, I assumed there there will be concrete below, because of only chipping out 2 inch PLUS the diameter of the conduit ( added for clarification to the poster) and pour 2" above creating the envelope.

    If the slab gets cut completely thru to earth, for some reason, then the conduit could be 12" deep providing there is a min of 2" of concrete above.

    In any case, this is going to be a tough install for a hot tub.
  • Jun 21, 2009, 09:40 AM
    stanfortyman
    I see that note, but never thought it applied to PVC. I have no idea what they mean by "Raceways approved for burial only".
    I see what you mean though by "concrete encased" and "envelope" as opposed to row four which refers to "under" a 4" slab.

    Either way, I do agree with you.
  • Jun 22, 2009, 05:40 PM
    brian421
    Quote:
    Originally Posted by brian421 View Post
    So for conduit my only option is THNN? Can't I use 1" conduit for 6/3 NM or UF?
    Another question... can I splice (through a J box) THHN and NM in my attic to avoid having to run conduit indoors?
  • Jun 23, 2009, 02:48 AM
    tkrussell
    Sure can, probably need an 8" x 8" x 4" JB.
  • Jun 23, 2009, 04:51 AM
    brian421
    Thanks, you have been a tremendous help!:)

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